Preparation method capable of controlling polyamide powder melt flow index

Abstract

The invention provides a preparation method capable of controlling polyamide powder melt flow index. The polyamide powder is obtained by steps: adding polyamide resin, a solvent and additives in a closed high-pressure reactor, leading in inert gas for protection, stirring continuously, heating to rise temperature until polyamide resin is dissolved in the solvent, continuing to rise temperature toreach the reaction temperature, holding the reaction temperature for a certain time, cooling to the room temperature, filtering by extraction, and drying finally; the polyamide powder melt flow indexis increased by increasing the reaction temperature and prolonging the time of duration of the reaction temperature that is higher than the dissolving temperature in the reaction. By the preparation method, the molecular weight of polyamide powder can be reduced in the preparation process thereof so that the melt flow index of the polyamide powder can be increased to improve processability of thepolyamide powder during the selective laser sintering, achieve excellent melt flowability of the polyamide powder after laser scanning, reduce internal defects of workpieces, improve mechanical property of the workpieces, improve surface quality of the workpieces and improve recyclability of the polyamide powder.

Description

technical field [0001] The invention belongs to the technical field of additive manufacturing, and in particular relates to a preparation method for controlling the melt flow index of polyamide powder. Background technique [0002] Selective laser sintering is a method of manufacturing three-dimensional objects by selectively fusing multiple layers of powder, which allows machining without tools but only by laser sintering multiple overlapping layers of powder according to the three-dimensional image of the object to be produced, to get a 3D solid. [0003] Selective laser sintering technology can prepare products with any complex structure within the size range, which is very effective for sample design, testing and even small batch manufacturing in the production process during the research and development process, but this manufacturing method will bring precision compared to traditional processes In many fields, users are very concerned about the surface quality and mec...

AI Technical Summary

Problems solved by technology

[0004] Polyamide powder is one of the main raw materials for selective laser sintering technology to manufacture three-dimensional objects. However, the selective laser sintering of polyamide powder in actual production often has poor surface quality and low reusability, which affects the appearance and One of the reasons for this problem is that the melt flow index of polyamide powder is low

In the selective laser sintering process, the time interval between laser scanning and the next layer of powder coating is short. If the polyamide powder melt flow index is too low, the melt fluidity will be poor, and it will not be fully leveled, which will affect the workpiece. The internal compactness leads to a decrease in mechanical properties; due to insufficient melt fluidity, the part will shrink unevenly during the cooling process, resulting in poor surface quality of the part; at the same time, when the remaining powder is used again, the flow index of the powder melt is further reduced. The mechanical properties and surface quality of the parts will be further deteriorated

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